1. Field of the Invention
The present invention pertains to surgical instruments for precisely positioning guide wires in bone allowing tunnels to be formed in the bone along the guide wires and, more particularly, to femoral guides for precisely positioning guide wires in the femur in cruciate ligament reconstruction of the knee allowing bone tunnels to be formed in the femur along the guide wires at sites anatomically equivalent to the cruciate ligament and to methods of precisely forming bone tunnels.
2. Description of the Prior Art
Various surgical procedures utilize graft or prosthetic ligaments to reconstruct natural ligaments that have been damaged by injury or disease. Where the ligaments to be reconstructed are found in joints or articulations of the body, i.e., the connections of the various surfaces of the bones in the body, graft or prosthetic ligaments are typically implanted and fixated in bones of the joint at sites anatomically equivalent to the natural ligament. In cruciate ligament reconstruction, such as anterior cruciate ligament reconstruction of the knee, tandem, isometrically positioned bone tunnels are formed, respectively, in the tibia and femur at sites anatomically equivalent to attachment of the anterior cruciate ligament, and a graft or prosthetic ligament having bone blocks at its ends is inserted in the bone tunnels to extend across the knee joint with the bone blocks disposed, respectively, in the bone tunnels. Interference bone fixation screws are inserted in the tibial and femoral bone tunnels to be positioned laterally between the bone blocks and walls of the bone tunnels to fixate the ligament and provide a bone-tendon-bone graft. In anterior cruciate ligament reconstruction of the knee, it is very important that the bone tunnels be located at the anatomic sites of attachment of the anterior cruciate ligament; and, where anterior cruciate ligament reconstruction is performed as an open surgical procedure utilizing relatively long incisions on the order of ten inches in length to access the knee joint, the increased room for maneuverability afforded by the long incisions can enhance proper placement of the tibial and femoral bone tunnels. However, open surgery possesses numerous disadvantages over closed, or least invasive surgery, including increased invasiveness and trauma, prolonged hospitalization and rehabilitation times, increased patient discomfort, possible violation of capsular mechanoreceptors, dessication of articular cartilage and delayed post-surgical mobility. Accordingly, it is preferred to perform anterior cruciate ligament reconstruction as a least invasive, closed, or endoscopic, procedure wherein portals of minimal size, such as are formed with a puncture or stab wound, in tissue adjacent the knee are utilized to access the knee joint with the knee being visualized with an arthroscope, the portals being just large enough to accommodate surgical instruments inserted at the knee joint. Arthroscopic anterior cruciate ligament reconstruction provides numerous benefits over open surgery including minimal invasiveness and trauma, performance on an out-patient basis, reduced rehabilitation time, decreased patient discomfort, early, aggressive range of motion, cosmetically pleasing incisions, completion with tourniquet times under one hour, the opportunity to perform a diagnostic arthroscopy without having to commit to anterior cruciate ligament reconstruction unless confirmed by the diagnostic findings and early weight bearing without loss of fixation.
Where cruciate ligament reconstruction is performed as a closed, or endoscopic, surgical procedure, the small size of the portals limits access to and maneuverability at the knee joint making it relatively more difficult to precisely place the tibial and femoral bone tunnels at sites anatomically equivalent to the cruciate ligament. In most cases, guide wires or pins are inserted through arthroscopic size portals from externally of the body and are driven, from externally of the body, in the tibia and femur at desired locations for longitudinal axes, or centers, of the tibial and femoral bone tunnels, allowing the bone tunnels to be formed along the guide wires, such as by drilling or reaming, substantially coaxially or concentrically with the guide wires. Although the guide wires are effective in guiding instruments, such as drills and reamers, utilized to form the bone tunnels, problems can arise in arthroscopic cruciate ligament reconstruction in precisely positioning or locating the guide wires. If the guide wires are not located and inserted at sites anatomically equivalent to attachment of the cruciate ligament, the tibial and femoral bone tunnels, as guided by the guide wires, will not be properly located, and ligament reconstruction will be impaired. In arthroscopic anterior cruciate ligament reconstruction, it is difficult to position a guide wire on the femur at a position corresponding to the anatomic center of attachment of the anterior cruciate ligament. In order to position a tip of the guide wire on the femoral condyle at the anatomic center for the anterior cruciate ligament and drive the guide wire into the femur such that a bone tunnel formed along the guide wire will have a longitudinal axis substantially aligned with the anatomic center of the anterior cruciate ligament, the guide wire must be inserted through a tibial bone tunnel from a portal of minimal size, and a tip of the guide wire must be located on the femoral condyle with the guide wire held and driven into the femur from externally of the knee. When positioning the tip of the guide wire on the femoral condyle, it is desired that the tip be positioned high in a notch on the femoral condyle, the notch being formed in a notchplasty procedure prior to formation of the bone tunnels, such that the longitudinal axis of the femoral bone tunnel will be disposed sufficiently anterior, i.e., approximately 6-7 millimeters, to the posterior edge or "over-the-top ridge" of the notch and the femoral bone tunnel will be as far posterior as possible while still allowing a tunnel and not a trough with the cortical margin of the femur being neither too wide nor too narrow. However, it is extremely difficult in arthroscopic anterior cruciate ligament reconstruction to position and hold the guide wire from externally of the knee such that the tip of the guide wire is optimally, isometrically positioned on the femur; and, even when properly positioned, the guide wire can slip or shift prior to being driven into the femur resulting in an improperly positioned femoral bone tunnel and impaired placement of the graft or prosthetic ligament. Where instruments are used to help guide or hold the guide wire, the instruments themselves can slip or shift causing displacement of the guide wire; and, frequently, the use of instruments does not eliminate the need for a surgeon to estimate where to place instruments such as drills or reamers when forming the femoral bone tunnel along the guide wire. Accordingly, arthroscopic anterior cruciate ligament reconstruction as presently performed lacks instruments for precisely positioning a guide wire on the femur at a site anatomically equivalent to the anterior cruciate ligament to allow a femoral bone tunnel formed substantially coaxially or concentrically along the guide wire to be optimally, isometrically positioned.